Field of the Invention
The present invention relates to a method and apparatus for dressing a wound and a method for manufacturing a wound dressing. In particular, but not exclusively, the present invention relates to a wound dressing useable during topical negative pressure (TNP) therapy in which the wound dressing itself acts as a waste canister to collect and store wound exudate removed from a wound site.
There is much prior art available relating to the provision of apparatus and methods of use thereof for the application of topical negative pressure (TNP) therapy to wounds together with other therapeutic processes intended to enhance the effects of the TNP therapy. Examples of such prior art include those listed and briefly described below.
TNP therapy assists in the closure and healing of wounds by reducing tissue oedema; encouraging blood flow and granulation of tissue; removing excess exudates and may reduce bacterial load and thus, infection to the wound. Furthermore, TNP therapy permits less outside disturbance of the wound and promotes more rapid healing.
In International patent application, WO 2004/037334, apparatus, a wound dressing and a method for aspirating, irrigating and cleansing wounds are described. In very general terms, the application describes the treatment of a wound by the application of TNP therapy for aspirating the wound together with the further provision of additional fluid for irrigating and/or cleansing the wound, which fluid, comprising both wound exudates and irrigation fluid, is then drawn off by the aspiration means and circulated through means for separating the beneficial materials therein from deleterious materials. The materials which are beneficial to wound healing are recirculated through the wound dressing and those materials deleterious to wound healing are discarded to a waste collection bag or vessel.
In International patent application, WO 2005/04670, apparatus, a wound dressing and a method for cleansing a wound using aspiration, irrigation and cleansing wounds are described. Again, in very general terms, the invention described in this document utilises similar apparatus to that in WO 2004/037334 with regard to the aspiration, irrigation and cleansing of the wound, however, it further includes the important additional step of providing heating means to control the temperature of that beneficial material being returned to the wound site/dressing so that it is at an optimum temperature, for example, to have the most efficacious therapeutic effect on the wound.
In International patent application, WO 2005/105180, apparatus and a method for the aspiration, irrigation and/or cleansing of wounds are described. Again, in very general terms, this document describes similar apparatus to the two previously mentioned documents hereinabove but with the additional step of providing means for the supply and application of physiologically active agents to the wound site/dressing to promote wound healing.
The content of the above-noted references is included herein by reference.
However, the above described apparatus and methods are generally only applicable to a patient when hospitalised as the apparatus used is complex, needing people having specialist knowledge in how to operate and maintain the apparatus, and also relatively heavy and bulky, not being adapted for easy mobility outside of a hospital environment by a patient, for example.
Some patients having relatively less severe wounds which do not require continuous hospitalisation, for example, but whom nevertheless would benefit from the prolonged application of TNP therapy, could be treated at home or at work subject to the availability of an easily portable and maintainable TNP therapy apparatus. To this end GB-A-2 307 180 describes a portable TNP therapy unit which may be carried by a patient and clipped to belt or harness. A negative pressure can thus be applied at a wound site.
During TNP therapy a portable or non-portable therapy unit generates a negative pressure at a wound site. As fluid, including air as well as wound exudate material is removed from the wound site this must be collected in some manner remote from the wound site. With prior known therapy units the collection and storage of wound exudate material is typically carried out by a waste canister connected to a pump unit of the therapy unit. The use of a canister, however, can result in the therapy unit apparatus itself being quite bulky and expensive to manufacture. Also replacing a canister or a bag in a canister in which wound exudate is collected can be a time consuming and relatively unhygienic process.
Prior known therapy units also tend to include a pump which is used to generate the negative pressure. Such pumps can be costly to manufacture and are relatively heavy.
WO 2007/030601, which is incorporated herein by reference discloses a self-contained wound dressing with a micro pump. The pump for drawing wound fluid into a vacuum zone is included in a wound dressing itself. Nevertheless wound exudate from the dressing can only be removed via a complex series of steps. The exudate removal process is also prone to contamination since once an absorbent layer is fully saturated with wound exudate an access door must be opened in the wound dressing so that the absorbent layer and micro pump can be removed. It will be appreciated that such exudate removal and pump removal can be time consuming and can lead to cross contamination between users. A further problem is that the wound dressing is prone to over expansion and rupture.